Configuration Method for a Synchronization Task from GaussDB Distributed in Single-Task Mode

Method 1: Modify the configuration file.

Procedure

Query the location of the configuration file.

find / -name "pg_hba.conf"
Or
find / -name "gs_hba.conf"

Open the pg_hba.conf file. Retain sha256 and insert trust of the specified single-mode task user in the line above sha256.
- CN configuration
  host replication <user> 0.0.0.0/0 sha256
  Figure 1 CN configuration
- DN configuration
  host replication <user> 0.0.0.0/0 trust
  
  Figure 2 DN configuration
  
  For the DN configuration, do not set <User> to all. Otherwise, connections to DNs on a distributed source instance in multi-task mode will be affected.
Run the following statement as a system administrator on the source database or restart the DB instance to apply the change:
```
select pg_reload_conf();
```

Method 2: Use gs_guc.

For a cloud database, run the following command to access the sandbox. For a self-built database, run the source gauss_env_file command to configure the environment variable file.

Log in to any database node, switch to user Ruby, and run the su - Ruby command.
1. Versions earlier than 2.0 (V500R002C00)
```
/usr/sbin/chroot /var/chroot /bin/bash
source /etc/profile && source ~/.bashrc
```
2. 2.0 (V500R002C00) and later versions
```
chroot /var/chroot
source /etc/profile; source /home/Ruby/.bashrc ;source /home/Ruby/gauss_env_file
```
To change a GaussDB instance on Huawei Cloud, you need to contact the database on-call personnel.
If only the single-task mode is used, the drs1 user is used as an example.

gs_guc reload -Z coordinator -N all -I all -h "host all drs1 0.0.0.0/0 sha256"

gs_guc reload -Z coordinator -N all -I all -h "host replication drs1 0.0.0.0/0 sha256"

Configure the replication connection between the CN and DN. The following uses network segment 192.168.0.0/16 of the CN as an example.

gs_guc reload -Z datanode -N all -I all -h 'host replication drs1 192.168.0.0/16 trust'

If only the multi-task mode is used, the drs2 user is used as an example.

gs_guc reload -Z datanode -Z coordinator -N all -I all -h "host all drs2 0.0.0.0/0 sha256"

gs_guc reload -Z datanode -N all -I all -h 'host replication drs2 0.0.0.0/0 sha256'

If you use both the multi-task and single-task modes for the same source instance, you are advised to plan migration users and configure the task as required.